Transparency and mechanical properties of PVA gels formed in DMSO/water (60/40) mixed solvent depend on gelation temperature.  We have revealed the formation mechanism such gels.  In a high temperature above room temperature spinodal decomposition type phase separation firstly occurs and then cross-linking reaction occurs in polymer-rich phase, giving a opaque macroscopic gel.  On the other hand, in a low temperature range blow about -20 C cross-linking reaction occurs in a homogeneous solution, giving a transparent gel, and after a while phase separation occurs against elastic force due to the network.